Recent advances in computed tomography (CT) technology allow for acquisition of two CT datasets with different X-ray spectra. There are different dual-energy computed tomography (DECT) technical approaches such as: the dual-source CT, the fast kilovoltage-switching method, and the sandwich detectors technique. There are various postprocessing algorithms that are available to provide clinically relevant spectral information. There are several clinical applications of DECT that are easily accessible in the emergency setting. In this review article, we aim to provide the emergency radiologist with a discussion on how this new technology works and how some of its applications can be useful in the emergency room setting.